Data Types Mapping

The Ingres .NET Data Provider defines its own enumeration of supported data types in addition to the standard System.Data.DbType enumeration.

The following table shows the mapping of the Ingres .NET Data Provider's data types to its .NET data type counterparts. For information on the typed accessors that a .NET application uses for an Ingres native database type to be obtained as a .NET type, see IngresDataReader Class.

IngresType	Ingres Data Type	Description	.NET Data Type
Binary	byte	Fixed length stream of binary data	Byte[ ]
Char	char	Fixed length stream of character data	String
DateTime	date	Date data	DateTime
Decimal	decimal	Exact numeric data	Decimal
Double	double precision (float8)	Approximate numeric data	Double
SmallInt	smallint	Signed 16-bit integer data	Int16
TinyInt	integer1	Signed 8-bit integer data	SByte
Int	integer	Signed 32-bit integer data	Int32
BigInt	bigint	Signed 64-bit integer data	Int64
LongVarBinary	long byte	Binary large object	Byte[ ]
LongVarChar	long varchar	Character large object	String
LongNVarChar	long nvarchar	Unicode large object	String
NChar	nchar	Fixed length stream of Unicode data	String
NVarChar	nvarchar	Variable length stream of Unicode data	String
Real	real (float4)	Approximate numeric data	Single
VarBinary	byte varying	Variable length stream of binary data	Byte[ ]
VarChar	varchar	Variable length stream of character data	String

Notes:

DateTime literals within SQL CommandText must be specified in the form of {d 'yyyy-mm-dd'} for dates and {ts 'yyyy-mm-dd hh-mm-ss'} for timestamps. However, it is preferable to pass .NET DateTime parameters rather than literals for these values.
For Ingres servers, DateTime parameters are converted to UTC values before being sent to the Ingres servers. DateTime values retrieved from Ingres servers are converted from UTC values to Local values. For non-Ingres servers, DateTime values are passed between the data provider and servers unchanged.

DbType Mapping

.NET's System.Data.DbType for a parameter is mapped to the IngresType data type as follows:

DbType	IngresType
AnsiString	VarChar
AnsiStringFixedLength	Char
Binary	VarBinary
Boolean	TinyInt, if supported by the database; otherwise, SmallInt
Byte	Binary, if supported by the database; otherwise, Char
Currency	Decimal
Date	DateTime
DateTime	DateTime
Decimal	Decimal
Double	Double
Guid	Not supported
Int16	SmallInt
Int32	Int
Int64	Decimal
Object	Not supported
SByte	TinyInt, if supported by the database; otherwise, SmallInt
Single	Real
String	NVarChar , if supported by the database; otherwise, VarChar
StringFixedLength	NChar, if supported by the database; otherwise, Char
Time	DateTime
UInt16	Int
UInt32	Decimal
UInt64	Decimal
VarNumeric	Decimal

Coercion of Unicode Strings

.NET strings are Unicode based. If the application is sending a Unicode string as a parameter to a database field that is ASCII char or varchar, the application can direct the data provider to coerce the Unicode string to an ASCII string on the client side by setting the IngresParameter's DbType property to DbType.AnsiString or the IngresType property to IngresType.VarChar.

The following is an example of coercing a Unicode string:

IngresCommand cmd = new IngresCommand(

    "select name from personnel where ssn = ?",
    conn);

IngresParameter parm =
    new IngresParameter("SSN", IngresType.VarChar);
parm.Value = strSSN;
cmd.Parameters.Add(parm);